The Power of Compound Interest Learn how to harness the power of compound interest for your investments. Related Content You May Need to Make Estimated Tax Payments If… Have income that isn’t subject to tax withholding? Or insufficient withholdings? You may have to pay estimated taxes. Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates. Pullbacks, Corrections, and Bear Markets When the market experiences volatility, it may be a good time to review these common terms.